I use a software called connecity ( http://connectify.me/ ) to turn my laptop to a wifi router and provide other devices with internet using my DSL connection. But after i switched to the ubuntu 11.10 I can't do this thing. Is there any linux software or trick available to do this?

there is bug currently in Ubuntu so there is work around for making ad hoc wifi access point, queting bellow:

"connecting with shared with other computers connection in NetworkManager. Other computer gets IP but NetworkManager disconnects the shared connection after half a second. This same setup worked perfectly fine in 11.04. Is there any fix, workaround or alternative way to share a connection with another computer over an Ethernet cable. (I can downgrade to 11.04 but I'd rather not ).

EDIT: found a workaround The workaround for now is to set IPv6 options to Ignore and then sudo killall dnsmasq. Reconnect and it should work."